[HerbertFriedman]

Just a data point. My 1972 came from the previous owner with a 12x12 Martec folding prop. I could not get the engine to rev up more than about 1200 rpm. I changed to a fixed 2 blade, 12x8 and the engine revved up to over 2000 rpm and ran well in forward but terribly in reverse (1972 Tartan 30. I finally changed to the fixed three blade 10x7 from Indigo, now preforms great in forward and reverse.